Hdri and background alpha

[gustav_gans]

Hi guys,

 

I have a scene with hdri light (like the blog entry by peter guthrie) and now I wonder how to get a proper alpha within photoshop to change the background image.

I've tried some render elements (background, matid,...) for the hdri-material but all render completely black.

 

Could you please give some advice?

 

Thanks, Klaus

[Nic H]

make the dome light invisible? render it on black and use the alpha to replace to your hearts delight. you could even put a rocketship in.

[gustav_gans]

@--

Thanks for your reply. Solves my problem perfectly!

Just because I'm curious, isn't there a chance to get a decent result with the main render?

[Nic H]

well you can put in a plane or geometry with your desired background image at the back of the scene

use a vray light mat with your texture and tick 'compensate camera exposure' to match it

 

but make sure its not visible to reflect/refract/shadow/everything in object properties

also make sure its not generating GI in vray properties - otherwise it will add a strange light to your scene.

 

there are probably easier ways tho!

[gustav_gans]

I do think I am blind. Where can I turn the dome light invisible (tried object properties und hide) - then I just deletet the dome light and everything worked fine...?

[Nic H]

dome light rollout

tick invisible

much the same as you would for a vray plane light

[gustav_gans]

sorry about that - works fine!!!